“He’s a very good man, he would be a good senator,” Reid said of Booker Thursday, noting he had previously spoken to the Newark mayor. “Of course we have to work out a few issues, but he would be a wonderful senator and he’s a great man.”

But in the subsequent conversation, Reid said he didn't want to make it appear that he was "dumping" on Lautenberg, saying, "That didn't sound too good to me."

"I always support incumbents and I always have and I wasn’t going to say anything bad about Cory Booker – he's a wonderful guy," Reid said.

Reid said he doesn't know if Lautenberg — who will turn 89 next month — will run in 2014.

Still, Reid's comments show how a Booker candidacy could face opposition from his party's establishment — if Lautenberg runs — even though the mayor is viewed as a rising Democratic star.

On Thursday, a Lautenberg spokesman dismissed questions over whether the senator would run, saying he was pushing to get a disaster relief bill through the Senate to help victims of Superstorm Sandy.

"This is not the time for political distractions, and the senator will address politics next year," said Lautenberg spokesman Caley Gray.